Valveless air hammer



my 24, 1923. i mamen J. E. HAGSTROM VALVELES S A I R HAMMER [1 Filed Feb. 2, 1920 l@ Fae-4- so A ' lNVENTOR JOSEPH E. HAGSTROM ATTORNEYS Patented duly 24%, 1923.

reati y JOSEPH E. HAGSTROM, OF CHICAGO, ILLINOIS.

VALVELESS AIR HAMMER.

Application filed February 2, 1920. Serial No. 355,807.

T 0 all whom t may concern.'

Be it known that I, JOSEPH E. LiGsrnoM. a subject of the King of Sweden, residing at Chicago, in the 'county of Cook and State of Illinois, have invented certain new and useful Improvements in Valveless Air Tflammers, of which the following is a specification.

The invention has for its general object the provision of an air hammer characterized by simplicity of parts 'and efficiency in operation, the peculiar construction of which results in economy of manufacture,

ready accessibility for cleaning or the replacement of parts, freedom from necessity of repair or adjustment, and efficient operation under all conditions of use.

A. particular object of the invention is the provision of such an implement wherein the construct-ion is such as to utilize effectively the kinetic power of the actuating fluid in addition to the actual pressure thereof, for the purpose of doing work.

Another particular object is the provision of such an implement wherein the friction of moving parts is materially eliminated and reduced.

A still further object is the provision of an implement having such a construction as will occasion the exhaust of a minimum amount of pressure fluid at each stroke.

Another object is the provision of a pneumatic hammer and similar implement wherein the construction is such as to effectively protect the device from the pounding of moving parts during its operation.

Other and further objects will be obvious from the following description and the drawings forming a part of this specificati-on, or indicated in the appended claims.

A description of the construction and operation of the improved hammer follows. It is to be understood, however, that the precise embodiment herein disclosed is to be considered as illustrative of rather than as unnecessarily limiting the scopo of the present invention.

In the drawings:

Fig. 1 is a side elevation of the air hammer, the barrel of which is partially broken away to show the interior parts at the end of the working stroke,

Fig. 2 is a top view of the same,

Fig. 3 is a. central longitudinal sectionk illustrating the parts at approximately the en d of the return stroke,

F ig. L1 is a fragmentary view, partially in section, showing tool insertedr in end of hammer,

Fig. 5 is a view similar to Fig. 4, but showing means for adapting-the old type ofv tool to this hammer.

Referring now in detail to the accompanying drawings, for purposes of exemplilica tion, the numeral 10 designates generally the frame member which is ofv an irregular shape and functions both as a handle and as a fra-me to which the body or barrel member 11 is attached. Said barrel. is held in position by a circular iiange 12 'extendingl from the frame 10. At one side the flange has cut in its periphery a narrow slot 13, and projecting outwardly on eachA side of said slot is a lug 14 perforated and threaded to receive a screw 15. By means of this screw the lugs 14C are drawn together causl ing the flange 12 to constrictively grip one 'end of the barrel 11'.

A rectangular key plug 1 6 having a semiciricular groove 17 cut in its outer' surface to receive the shank ofthe screw 15 fits snugly in the slot 13. rllhe inner surface of said plug contacts with the barrel 11 and a protruding stud 18 seats in a hole 19 of the barrel, thus securing said barrel to the frame against both angular and longitudinal movement as long as the screw 15 is in its operative position. s

At the other end of the barrel 11 is a reducing bushing 2O which is either formed integral with or secured rigidly within the said barrel. This bushing receives the shank of a removable tool 21, orif it so happens that the tool shank is of small diameter, an auxiliary bushing 22 may readily be brought into use. Another function of the bushing 2O is to form an annular groove 23 within which seats one end of the operating coil spring 24.

A handle 25 is formed in the frame 10 and has cut in its upper portion a slot 26. This slot is designed to receive the finger operated levers 27 and 28 which are pivotably mounted on the pins29 and 30 respectively. Th'ese pivot pins extend into the opposing walls of the slot 26, and the ends of CIT the pins are flush with the sides of the handle 25. Situated in the iframe l0 is a vertical bore 31 extending inwardly from the top ot the head member and from the inner end of the bore 3l, a much smaller bore 32 which serves as an oil drain, continues to the opposite side of said frame.

A cylindrical slide valve plug 33 lits snugly in the bore 31 and has intermediate its length an annular groove 34. Fositioned by` a lug 35 atthe bottom of the valve plug 33 is a compression spring36 which tends to expel the valve plug and hold its outer end in Contact with the pivoted arm 2S which, when the thumb piece 37 of the lever 27 is depressed, forces the valve plug inwardly `aga-inst the compression of spring 36, thus causing the groove 34 to register in hori- Zontal alinement with an air supply passage 33 through the frame. This air passage33 terminates in an enlarged portion 39 which is suitably tapped to receive a threaded air hose connection.

Concentric with the lange`l2`and the horizontal portion of the passage 33 is a cylindrical boss 40 oic the trame-l0. This projection has'a threaded horizontal hole 41 in its center, and is both alined with and connected to the heretofore-mentioned passage 38.

A centrallylocated guide rod or core 42 vwhich contains a passage 43 through approximately halt of' its length, has a threaded connection at one end in recess 4l. A lock nut 42, similarly threaded tixedly secures the rod 42 in the frame and prevents accidental displacement. The passage 43 is thus permanently alined with and forms a continuation of the passage 33 throughk the frame of the air hammer.

At a point corresponding to the termination of the passage 43 on the guide rod 42 is an egg-shaped enlargement 44, all vertical transverse sections of which are circular. This enlargementmay be either constructed integral with the shalt 42 or may be rigidly positioned therewith. A plurality of radially disposed ports 45 lead obliquely from the passage 43 to the forward face Vof the enlargement 44. The remainder of ythe rod 42 from the `enlargement 44 to its forward end 46, which seats loosely in a recess in the end or the tool 2l and which recess in turn acts as a brace for said rod, is preferably solid and functions as a guide for the hammer piston 47 which lits snugly and is longitudinally movable thereon. The piston member 47 is of cylindrical cup shape, its outer diameter being slightly less than that of the inside of the barrel ll so as to be out of contact therewith. At its forward end vthe piston diameter is reduced as at 43 to form a seat for one end of the heretofore mentioned coil spring 24. I

The inside of the marginal portion of the piston 47 is reamed out at a constant diameter for a portion o'l its lengthpas at 49,

in order to telescope the corresponding cylindrical portion 50 of the enlargement ot' core 42. A t a point adjacent the exterior openings o the radial ports -45 the interior recess of the piston member 47 tapersdownto a point approximately in lateral alinement with ythe annular abutment 48El on the exterior ot the hammer member, thus presenting a cuneiiiorm recess to receive the forward portion of the reaction member 44 but of greater depth and more gradual slope. From the point 52 to the end oit the interior bore oi' the piston member this portion acts as an air tight'sleeve insliding relationy to the solidz cylindrical portion 53 of the guide rod or core 42.V

An exhaust vent 54 is formed between the barrel and frame members by the slot i3 while two additional exhaust vents 55 may be provided'as shown.

The operation of this pneumatic hainmer is as l'ollows: l l

A fluid, preferably air, is admitted under pressure by means ot some approved hose connection to the 33 by way of the enlarged opening 39. lnasmuch as the annular groove 34 in the cylindrical valve plug is normally not in alinement with the horizontal passage 38, the compressed air in said passage is electually shut off from the operating mechanism ot the hammer. ln order to operate the pneumatic hammer the thumb piece 37 is pressed, and the cylinder 33 is in consequence forced downwards. he annular groove 34 coming into alinement with the passage 38 permits the compressed lair in said passa-ge to pass into the duct 43 of the core 42. y duct is led through the radial ports 45 and iinpinges against the cuneil-orm surface `5l or the piston, as a result of which said pis- 'ton is driven forcibly forward, compressing the spring 24, untilthe forward end y56 of the piston strikes the end 57 ol' the tool 2l. When this point is reached the piston has traveled suiiiciently forward for the rim to clear the portion 50 ofthe enlargement and `to uncover the ports 45, thus allowing the compressed air to escape into the barrel 1l and to exhaust through the heretofore mentioned vents and 55. rlhe torce oit the compressed air non" being removed from behind the piston, the stressed ycoil springI 24 forces the piston back intoits vnormal position, and the reciprocating action ofthe hammer member' is rapidly and continuously repeated so long as the valve plug is held in open position by the thumb piece.

From the foregoing` description, it will be observed that my improved construction employs butr a single moving part, viz, the striker 47. which delivers its work blow directly against the tool, and which, on its The compressed air in said return stroke, is stopped by the pressure :fluid before it has opportunity of striking a blow on any abutting portion of the device, The direct impingement of the actuating fluid from the ports Ll5 upon the surface of the movable striker, and particularly upon said surface at an angle with respect to the direction of travel of the striker, utilizes effectively the kinetic power of the pressure fluid. The diverging relationship of the wall 51 relative to the tapering wall of the reaction member forms an expansion nozzle through which thepressure fluid is injected, whereby its velocity is increased. The relationship of the wall 5l to the sides of the guide 53 forms a contracting chamber with the wall of the striker in position to receive the injected fluid. By this arrangement the effectiveness of the pressure fluid for propelling the striker is augmented. By virtue of this construction, furthermore, the increase in cubic capacity of the pressure chamber by movement of the striker is relatively small, so that a high compression is effected and only a small amount of pressure fluid exhausted at each stroke. rfhe construction is also effective to materially reduce the friction area between the moving parts, as the strikeris carried on the small diameter guide 53 and has but small surface bearing on the cylindrical portion 50, and has ,no friction engagement with the barrel ll.

lt will be understood that any pressure fluid may be used as a motive force and that the term air is used in a general sense; also that other terms used in connection with the particular embodiment of the invention shown and described are to be construed liberally.

l claim:

l. In an air hammer, the combination of a barrel providing a tool mounting in its forward end, a rod fixed axially in thebarrel and having thereon an enlargement with a forwardly coned face, the rod having an air passage therethrough with ports opening to its face, a cup-like piston guided within the barrel in advance of the enlargement, a spring forcing the piston rearwardly and means to control the air supply to the ports.

2. In an air hammer.' the combination of a barrel providing a tool mounting in its forward end, a rod fixed axially in the barrel `and having thereon an enlargementwith a forwardly coned face, the rod having an air passage therethrough with ports opening obliquely to its face, a cup-like piston guided within the barrel and having a rearwardly opening recess to receive the enlargement and to conform approximately in shape to the face thereof, a spring forcing the piston rearwardly and means to control the air supply to the ports. i

3. In an air hammer, the combination of means to control the air supply to the ports Ll. In an air hammer, the combination of a barrel providing a tool mounting in "its forward end,a'rod fixed axially in the barrel and having'thereon an enlargement with a forwardly coned face intermediate its length, the rod having an air passage therethrough with forwardly directed ports opening at the enlargement thereof obliquely to its face, a cup-like piston guided within the barrel on the rod vin advance of the enlargement, the'piston having a rearwardly open` ing recess corresponding in shape approximately to the coned face of the enlargement vbut of greater depth and with the inner diameter of its rim corresponding to the outer diameter of the enlargement at the rear of.

the ports and exten ding beyond said ports, a

springforcing the piston rearwardly and i mea-ns to control the air supplyto the'ports Awhereby in 'the rearmost position ofthe piston the air will be directed into the recess in advance of the enlargement to propel theA piston `forwardly and uncovered y the l'ports whereupon the air will be free to exhaust until the spring returns the piston and again closes olf the the escape around the enlargement. 7 Y

5. In an air hammer, the combination of a frame providing a handle, a boss, and a split flange about the boss, said frame having a valve controlled air passage through the boss, a barrel clamped within the split flange about the boss and providing at its forward end a tool mounting, a rod having connection with the boss and disposed axially within the barrel, the rod having an air passage therethrough with ports opening to its surface, a piston guidedwithin the barrel on the rod in advance ofthe ports, and a spring forcing the piston rearwardly. y i

5. In an air hammer, the combination of a frame, providing a handle7 a boss, anda split flange aboutV the boss, said frame having a valve controlled air passage through the boss, a barrel disposed within the split flange about the boss, a set screw bridging the split in the flange to clamp the same upon the barrel, a key engaged by thescrew and having a studengaging the barrel to Aform an interlocking engagement between the barrel and flange, said lbarrel providing at its forward end av tool mounting, a member having f connection with the boss and disposed axially within the barrel, said member having an air passage therethrough with ports openingto its surface, a piston guided Within the barrel on said member 1n advance ot the ports, and a spring forcing rthe pistonrear- Wardly.

l7. ln an air hammer, the combination of" a frame providing a handle, a boss, a split flange about the boss, said frame having a valve controlled air passage through the boss, a barrel clamped Within the fiangeY in spaced relation to the boss and providing at Adepth than the coned enlargement and adapted to receive the same. the rim'vof the recess extending` rearwardly beyond `the ports and havingl an interior diameter corresponding to the exterior diameter ot the enlargement at the rear of the ports, a compression spring `disposed in advance of the piston Where-by in the rearmost position ot .the piston the air Will be directed through the portsv into the recess. in advance ot the enlargement to propel the piston forwardly and uncover the ports by the rim whereupon the air will be tree to exhaust until the spring returns. the piston and again closes off the escape around lthe enlargement.

8. A pneumatic engine and the like, comprising a trame affording free mounting for a tool, an axial guide member, a striker slidably mounted on the guide member for engagement with a tool in the mount-ing, yielding pressure means for'retracting the striker from the mounting, said striker being formed with a tapered axial chamber, a member in alignment with the guide torminga closure io'rv said chamber when the striker is in retracted position, said member being provided vvith channels tor directing pressure fluid against the Wallet said chamber when it is closed, and means for controllingsupply of pressure fluid to said channels.

9. ln a device ofthe class described, the combination of a frame'afl'ordinga mounting for a tool, a guide supported on the frame for alignment With a tool supported von said mountinga striker mounted on said guide for reciprocating,movement toward and from such tool, said striker being formed with an internal cavity having a 'lateral Wall converging toward the guide, a member supported on the frame in alignment vvith the guide for insertion into said cavity and elective to close the same during a portion of the travel ot the striker,

.striker having a rearwardly opening axial cavity withv Walls converging toward the tool mounting, a member mounted on the `frame for reception into said cavity and provided ivith a duct arranged to direct pressure fluid against the Wall thereof, a member arranged to close the cavity during 'a portion of the travel ot the striker, said striker being movable to clear -said last mentioned member, yielding means for moving the striker from the tool mounting, and means for controlling supply of pressure fluid to said duct.` y i 1l. In a device of the class described, the combination of a frame supporting a tool mounting, a striker slidably mounted on said frame for movement toward and from the tool mounting` said striker being provided With an i axial cavity of decreasing,

area toivard the toolmounting, a member mounted on the frame .and having taperand having a tapering portion directed toward the tool mounting, a striker mounted for movement trom said member to the tool mounting and providedjyith a tapering cavity arranged to receive said member, yielding means for moving the striker onto saidv member, said member being provided With a duct` arranged to inject fluid betvveen its tapering1 portion and the striker, and means\ for controlling the supply of pressure fluid to said duct.

13. ln a device ot the class described, the combination of a trame, a tool mounting supported thereon, a reaction member Supported on the trame in alignment With the tool mounting, said member being provided withv a duct, a striker slidably mounted on the framefor movement over said member and toward the tool mounting and provided with a side Wall extending at an angle to its direction of travel in position for impingement of fluid from said duct, means for controlling supply ot pressure fluid to the duct and means for retracting the striker.

14. In a device of the class described, the combination of a frame aording a mounting` for a tool, a striker mounted for reciprocation on said :frame toward and from the tool mounting, said striker having a cavity with converging lateral walls, a vreaction member mounted on the frame in position to be received into said cavity, means for injecting fluid into the cavity between the reaction member and said lateral walls of the striker, and means for moving the striker to receive the reaction member.

15. In a device of the class described, the combination oii a frame affording a tool mounting, a. striker mounted on said frame for reciprocatory movement, said striker being provided with a longitudinally extendaction member mounted on t-he frame for reception into said cavity, ysaid reaction member having an oblique lateral wall portion, means for injecting pressure iiuid between said oblique wall portion and the lateral wall of the cavity, and means for effecting movement of the striker o-nto the reaction member.

16. In a device or" the class described, the combination of a frame, a tool mounted thereon, a reaction member and a striker arranged for relative telescopic movement yon the frame to provide a pressure chamber between them, the striker being. movable off of the reaction member tostrike the tool, the reaction member affording a conduit for injection of fluid into the pressure chamber, the striker having parts eiective during its movement to vent and close the compression chamber to atmosphere, and means tor controlling supply of pressure Huid to the pressure chamber.

17. In a device of the class described, the combination of a frame, a reaction member and striker mounted thereon for relative telescopic movement, atool movably mount ed on the frame in position to be struck by the striker, means being provided for effecting movement of the striker trom the tool, said reaction member and striker having cooperating faces arranged to form a pressure chamber, a channel being providedl for introduction of pressure Huid into said chamber, and the opposed walls of the chamber diverging from said duct.

18. In a device of the class described, the combination of a frame, a reaction member and striker mounted `thereon for relative telescopic movement, means being provided for eecting movement of the striker onto the reaction member, a tool supported on the Jframe in position to be struck by the striker, said reaction member and striker having cooperating walls disposed to iorm a pressure chamber, a duct being provided for introduction of pressure fluid into said 1n@ cavitT o en at its rearward end a rechamber, and opposed walls of'said chamber first diverging Vand then converging from the duct toward the tool.

` 19. In a device of the class described, the

combinationl of a frame, a toolv mounted thereon, a striker movableon the frame into contact with the tool, a reaction member mounted on the frame for cooperation with the striker to form a pressure chamber, the

striker being arranged to telescope the reacmember.

20. In a device of the class described, the combination with a tool of a striker movable into engagement therewith, said striker having a bore extending longitudinally therethrough a reaction member cooperating with the striker, and a guide member upon which t-he striker is supported, said guide member and reaction member ldisposed to close the opposite ends ot the bore o'i the striker to form a pressure chamber, a duct being provided for introduction of pressure fluid into such chamber.

21. In a device of the class described, the combination with a tool, of astriker movable into contact therewith, said striker being provided with an internal cavity, a guide upon which the striker rides forming a closure for said cavity at one end,'a reaction member cooperating with the striker to form a closure for said cavity at the other end, a duct being provided for introduction of pressure fluid into the cavity and means operable to effectreturn of the striker.

22. InV a device of the class described, `the combination with a tool of'a strikermovable into engagement therewith, a member disposed axially of said striker and cooperating therewith to form a pressure chamber, means being provided to effect movement of the striker onto said member, a duct being provided for introduction of pressure uid vinto said chamber, said striker and axial member having diverging wall portions adjacent the conduit opening and converging wall portions between the latter and the tool.

23. In a device ofthe class described, the combination of a reaction member, a tool, a striker mounted for reciprocatory movement relative to them and adapted to strike the tool, said reaction member and striker having portions cooperating to aiord apressure chamber1 and including means forming an expansion vnozzle arranged to direct pressure fluid into said chamber.

24. In a device of the class described, the combination with a tool of a reaction member, a striker member movable relative therellO *co7 one of seid members being provided withy n Witness whereof, I hzwe hereunto signed a eawlty arranged to receive the other theremy'naine 1n the presence'of two subscribing of, said cavity having a lateral Wall con- Wtnesses. y verging toward the tooh and Ineens for JOSEPH E. HAGSTBOM. injecting pressure fluid between said con- Witnesses: verging Wall and a lateral yWall of the other 'LEWIS T. GREIST,

v member. Y RAYMOND L. `(urinars'r. 

